1. Field of the Invention
The present invention relates to a valve for regulating a flow of gas, of the type have a valve body with an inlet for the gas to be regulated and an outlet for a regulated flow of a fluid, a valve seat with a valve opening, a moving closure part having a tensioned membrane mounted inside the valve body and a plunger, which is movable by an actuator arrangement, whose end acts on the membrane, causing the closure part to close and open the valve opening and regulate the flow of gas through same.
2. Description of the Prior Art
A valve of the above general type is shown and described in U.S. Pat. No. 5,265,594. It is highly important, particularly in the supply of gas to a patient on a ventilator, to ensure that the amount of gas supplied through such a valve is regulated with great accuracy and repeatability. In order to achieve this, the membrane must lift off the valve seat, parallel to same, every time the valve opens. When the membrane is closed with by the end of the plunger, which is flat with a surface area somewhat larger than the surface area of the valve seat, the end of the plunger must press against the valve seat with an evenly applied force. This can sometimes be difficult to achieve, since the valve seat and plunger are not always perfectly aligned. If their positions are disturbed so e.g. the plunger tilts in relation to the valve seat, this tilted, often uncontrolled, plunger position can result in leakage between the membrane and valve seat and to impaired regulation of gas flow through the valve. Even small angular deviations can greatly impair regulation of the flow of gas.